1. Field of the Invention
This invention relates to circuits for measuring heart pacer parameters, and, more particularly, to a circuit for measuring the refractory period of a heart pacer.
2. Description of the Prior Art
Although in the past heart pacers have been proposed which present variable refractory periods, in so far as is known to applicant, no circuits have been proposed which measure the refractory period of a heart pacer.
More particularly, the refractory period of a heart pacer is generally known as the time period after the delivery of a stimulation pulse to the patient's heart or after the production of a naturally produced heart wave during which the heart pacer is insensitive to electrical signals which may be received by it. Thus, for example, in the case of a demand heart pacer, if a signal having the characteristics of a naturally produced R-wave is received within the refractory period of a heart pacer, the heart pacer will, nevertheless, deliver a stimulation pulse at the predetermined timed period after the last stimulation pulse or after the last naturally produced heart pulse. On the other hand, if such signal is received at a time period beyond the refractory period of the pacer, the pacer will be reset to reinitiate its timing of the next to be delivered stimulation pulse from the reception of the electrical pulse.
What is needed, therefore, is a means for accurately measuring the refractory period of a heart pacer under consideration to determine whether the refractory period presented thereby is of proper length.